Generally, a computer is formed by a motherboard, a display and input/output devices (such as a keyboard or a mouse). However the prior art arrangements are determined in the manufacturing process.
Referring to FIG. 1, in one prior art compute mainframe arrangement, a compact disk drive or a hard disk drive is installed at a front surface of a computer casing. A lateral plate serves to install a motherboard. An interface card is inserted into the motherboard. A power module is installed at a rear end of the casing with a window. Thereby above-mentioned elements are connected by bank wires so as to form a computer. This prior art assembly way has been used for a long time and is not changed.
However with the improvement of technology, computers are used as daily work devices. Also, old styles of computer components are substituted continuously by new styles. Because of the improvement of computer components in quality, consumers are encouraged to purchase new style computers. In other hand, the new style components offer opportunity for users to upgrade their computers. Therefore, because manufacturers should consider the needs of consumers in detail so as to causes troubles in preparing materials, assembling, testing and stocks, these manufacturers must provide different options to computer components with various grades for consumers depending on consumer demands. From consumer standpoints, they may face the situations of computer upgrading or maintenance after a time period use. Because layouts of computer circuits are too complicated for people, it is difficult for people to upgrade and maintain computer. Besides, because a computer has a large size and the weight of the computer is heavy, it is inconvenient for users not only to transport the computer to a maintaining center, but also the computer occupies a large space for storage. In above mentioned prior art, computer components are connected each other by bank circuits to form a main board. Several defects are described as the followings. First of all, a manufacturer must increase cost for buying some bank circuits. Secondly, the assembly of the prior art causes chaos in circuits inside the computer casing. Because every component is corresponding both to an independent power circuit and a bank circuit for transmission data to a main board bidirectionally, the computer is ordinarily equipped at least one CD-ROM drive and a hard disk drive for accessing data. Various circuit cause a complicated structure inside the computer casing so as to frustrate the DIY users. Thirdly, a computer system of the prior art is easy to breakdown, because bank circuits are incorrect or has improper connections. Therefore, it is necessary to redefine and rearrange the positions of components inside a computer so as to reach the goals of convenient use and expansibility.